Evidence for a pharmacological interaction between ethanol and nicotine indicates that these two commonly used drugs may share some mechanisms of action . One such site of action may be the direct interaction of ethanol with nicotinic receptors. It has been noted that mice that have been made tolerant to the effects of nicotine by chronic treatment with this agent also show some tolerance to the acute effects of ethanol, that is some cross-tolerance between these two drugs occurs. As a first step in the investigation of the role of nicotinic receptor subtypes in influencing response to ethanol, the evaluation of the effects of chronic nicotine treatment on the expression of message and the localization of this message is proposed. Nice that have been chronically treated with nicotine (at various dosage levels and for various lengths of time) will be evaluated using methodologies available in the laboratory of Dr. Stephen Heinemann. His laboratory has cloned, sequenced, and localized several subtypes of both acetylcholine binding and structural subtypes of the nicotinic receptor. The experiments of the effects of chronic nicotine treatment on the level of expression of the nicotinic receptor subtypes will prepare the laboratory of the visiting scientist to further pursue the question of ethanol/nicotine interactions using the techniques of modern molecular biology.